Press releases November 2010http://press.cern/press-releases/2010/11/des-atomes-d%E2%80%99antimati%C3%A8re-produits-et-captur%C3%A9s-au-cern?created=
CERN press office - press releasesenLHC experiments bring new insight into primordial universehttp://press.cern/press-releases/2010/11/lhc-experiments-bring-new-insight-primordial-universe
<span class="submitted-by">26 Nov 2010</span>
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<p>Geneva, 26 November 2010. After less than three weeks of heavy-ion running, the three experiments studying lead ion collisions at the LHC have already brought new insight into matter as it would have existed in the very first instants of the Universe’s life. The ALICE experiment, which is optimised for the study of heavy ions, published two papers just a few days after the start of lead-ion running. Now, the first direct observation of a phenomenon known as jet quenching has been made by both the ATLAS and CMS collaborations. This result is reported in a paper from the ATLAS collaboration accepted for publication yesterday in the scientific journal Physical Review Letters. A CMS paper will follow shortly, and results from all of the experiments will be presented at a seminar on Thursday 2 December at CERN<sup><a href="#footnote1">1</a></sup>. Data taking with ions continues to 6 December.</p>
<p><em>“It is impressive how fast the experiments have arrived at these results, which deal with very complex physics,” </em>said CERN’s Research Director Sergio Bertolucci<em>. “The experiments are competing with each other to publish first, but then working together to assemble the full picture and cross check their results. It’s a beautiful example of how competition and collaboration is a key feature of this field of research.”</em></p>
<p>One of the primary goals of the lead-ion programme at CERN is to create matter as it would have been at the birth of the Universe. Back then, the ordinary nuclear matter of which we and the visible Universe are made could not have existed: conditions would have been too hot and turbulent for quarks to be bound up by gluons into protons and neutrons, the building blocks of the elements. Instead, these elementary particles would have roamed freely in a sort of quark gluon plasma. Showing beyond doubt that we can produce and study quark gluon plasma will bring important insights into the evolution of the early Universe, and the nature of the strong force that binds quarks and gluons together into protons, neutrons and ultimately all the nuclei of the periodic table of the elements.</p>
<p>When lead-ions collide in the LHC, they can concentrate enough energy in a tiny volume to produce tiny droplets of this primordial state of matter, which signal their presence by a wide range of measureable signals. The ALICE papers point to a large increase in the number of particles produced in the collisions compared to previous experiments, and confirm that the much hotter plasma produced at the LHC behaves as a very low viscosity liquid (a perfect fluid), in keeping with earlier observations from Brookhaven’s RHIC collider. Taken together, these results have already ruled out some theories about how the primordial Universe behaved.</p>
<p>“<em>With nuclear collisions, the LHC has become a fantastic 'Big Bang' machine,”</em> said ALICE spokesperson Jürgen Schukraft. <em>“In some respects, the quark-gluon matter looks familiar, still the ideal liquid seen at RHIC, but we’re also starting to see glimpses of something new.”</em></p>
<p>The ATLAS and CMS experiments play to the strength of their detectors, which both have very powerful and hermetic energy measuring capability. This allows them to measure jets of particles that emerge from collisions. Jets are formed as the basic constituents of nuclear matter, quarks and gluons, fly away from the collision point. In proton collisions, jets usually appear in pairs, emerging back to back. However, in heavy ion collisions the jets interact in the tumultuous conditions of the hot dense medium. This leads to a very characteristic signal, known as jet quenching, in which the energy of the jets can be severely degraded, signalling interactions with the medium more intense than ever seen before. Jet quenching is a powerful tool for studying the behaviour of the plasma in detail.</p>
<p>“<em>ATLAS is the first experiment to report direct observation of jet quenching</em>,” said ATLAS Spokesperson Fabiola Gianotti. “<em>The excellent capabilities of ATLAS to determine jet energies enabled us to observe a striking imbalance in energies of pairs of jets, where one jet is almost completely absorbed by the medium. It’s a very exciting result of which the Collaboration is proud, obtained in a very short time thanks in particular to the dedication and enthusiasm of young scientists.</em>”</p>
<p><em>“</em><em>It is truly amazing to be looking, albeit on a microscopic scale, at the conditions and state of matter that existed at the dawn of time,” </em>said CMS Spokesperson Guido Tonelli. <em>“Since the very first days of lead-ion collisions the quenching of jets appeared in our data while other striking features,</em> <em>like the observation of Z particles, never seen before in heavy-ion collisions, are under investigation. The challenge is now to put together</em> <em>all possible studies that could lead us to a much better understanding of the properties of this new, extraordinary state of matter." </em></p>
<p>The ATLAS and CMS measurements herald a new era in the use of jets to probe the quark gluon plasma. Future jet quenching and other measurements from the three LHC experiments will provide powerful insight into the properties of the primordial plasma and the interactions among its quarks and gluons.</p>
<p>With data taking continuing for over one more week, and the LHC already having delivered the programmed amount of data for 2010, the heavy-ion community at the LHC is looking forward to further analysing their data, which will greatly contribute to the emergence of a more complete model of quark gluon plasma, and consequently the very early Universe.</p>
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<p>CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. Israel is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.</p>
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Fri, 26 Nov 2010 09:00:00 +0000Cian O'Luanaigh113 at http://press.cernAntimatter atoms produced and trapped at CERNhttp://press.cern/press-releases/2010/11/antimatter-atoms-produced-and-trapped-cern
<span class="submitted-by">17 Nov 2010</span>
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<p>Geneva, 17 November 2010. The ALPHA experiment at CERN<sup>1</sup> has taken an important step forward in developing techniques to understand one of the Universe’s open questions: is there a difference between matter and antimatter? In a <a href="http://dx.doi.org/10.1038/nature09610">paper published in <em>Nature</em> today</a>, the collaboration shows that it has successfully produced and trapped atoms of antihydrogen. This development opens the path to new ways of making detailed measurements of antihydrogen, which will in turn allow scientists to compare matter and antimatter.</p>
<p>Antimatter – or the lack of it – remains one of the biggest mysteries of science. Matter and its counterpart are identical except for opposite charge, and they annihilate when they meet. At the Big Bang, matter and antimatter should have been produced in equal amounts. However, we know that our world is made up of matter: antimatter seems to have disappeared. To find out what has happened to it, scientists employ a range of methods to investigate whether a tiny difference in the properties of matter and antimatter could point towards an explanation.</p>
<p>One of these methods is to take one of the best-known systems in physics, the hydrogen atom, which is made of one proton and one electron, and check whether its antimatter counterpart, antihydrogen, consisting of an antiproton and a positron, behaves in the same way. CERN is the only laboratory in the world with a dedicated low-energy antiproton facility where this research can be carried out.</p>
<p>The antihydrogen programme goes back a long way. In 1995, the first nine atoms of man-made antihydrogen were produced at CERN. Then, in 2002, the ATHENA and ATRAP experiments showed that it was possible to produce antihydrogen in large quantities, opening up the possibility of conducting detailed studies. The new result from ALPHA is the latest step in this journey.</p>
<p>Antihydrogen atoms are produced in a vacuum at CERN, but are nevertheless surrounded by normal matter. Because matter and antimatter annihilate when they meet, the antihydrogen atoms have a very short life expectancy. This can be extended, however, by using strong and complex magnetic fields to trap them and thus prevent them from coming into contact with matter. The ALPHA experiment has shown that it is possible to hold on to atoms of antihydrogen in this way for about a tenth of a second: easily long enough to study them. Of the many thousands of antiatoms the experiment has created, ALPHA’s latest paper reports that 38 have been trapped for long enough to study.</p>
<p>“For reasons that no one yet understands, nature ruled out antimatter. It is thus very rewarding, and a bit overwhelming, to look at the ALPHA device and know that it contains stable, neutral atoms of antimatter,” said Jeffrey Hangst of Aarhus University, Denmark, spokesman of the ALPHA collaboration. “This inspires us to work that much harder to see if antimatter holds some secret.”</p>
<p>In another recent development in CERN’s antimatter programme, the ASACUSA experiment has demonstrated a new technique for producing antihydrogen atoms. In a paper soon to appear in Physical Review Letters, the collaboration reports success in producing antihydrogen in a so-called Cusp trap, an essential precursor to making a beam. ASACUSA plans to develop this technique to the point at which beams of sufficient intensity will survive for long enough to be studied.</p>
<p>“With two alternative methods of producing and eventually studying antihydrogen, antimatter will not be able to hide its properties from us much longer,” said Yasunori Yamazaki of Japan’s RIKEN research centre and a member of the ASACUSA collaboration. “There’s still some way to go, but we’re very happy to see how well this technique works.”</p>
<p>“These are significant steps in antimatter research,” said CERN Director General Rolf Heuer, “and an important part of the very broad research programme at CERN.”</p>
<p>Full information about the ASACUSA approach will be made available when the paper is published.</p>
<ul><li><a href="http://cerncourier.com/cws/article/cern/30577">Further information on ALPHA</a></li>
<li><a href="http://cdsweb.cern.ch/record/1307522">Photos</a></li>
<li><a href="http://cdsweb.cern.ch/record/1307524">Video</a></li>
</ul><h3>Contact</h3>
<p>Jeffrey Hangst, ALPHA experiment spokesperson</p>
<p>+41 76 487 45 89</p>
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<p>CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. Israel is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.</p>
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Wed, 17 Nov 2010 09:00:00 +0000Cian O'Luanaigh115 at http://press.cernCERN completes transition to lead-ion running at the LHChttp://press.cern/press-releases/2010/11/cern-completes-transition-lead-ion-running-lhc
<span class="submitted-by">08 Nov 2010</span>
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<a href="http://press.cern/sites/press.web.cern.ch/files/image/press/old/ALICE%20lead.jpg"><img typeof="foaf:Image" src="http://press.cern/sites/press.web.cern.ch/files/image/press/old/ALICE%20lead.jpg" width="523" height="385" alt="" /></a> </div>
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<p>An event recorded by the ALICE experiment from the first lead-ion collisions, at a centre-of-mass energy of 2.76 TeV per nucleon pair</p>
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<p>Geneva, 8 November 2010. Four days is all it took for the LHC operations team at CERN<sup><a href="#footnote1">1</a></sup> to complete the transition from protons to lead ions in the LHC. After extracting the final proton beam of 2010 on 4 November, commissioning the lead-ion beam was underway by early afternoon. First collisions were recorded at 00:30 CET on 7 November, and stable running conditions marked the start of physics with heavy ions at 11:20 CET today.</p>
<p>“The speed of the transition to lead ions is a sign of the maturity of the LHC,” said CERN Director General Rolf Heuer. “The machine is running like clockwork after just a few months of routine operation.”</p>
<p>Operating the LHC with lead ions – lead atoms stripped of electrons - is completely different from operating the machine with protons. From the source to collisions, operational parameters have to be re-established for the new type of beam. For lead-ions, as for protons before them, the procedure started with threading a single beam round the ring in one direction and steadily increasing the number of laps before repeating the process for the other beam. Once circulating beams had been established they could be accelerated to the full energy of 287 TeV per beam. This energy is much higher than for proton beams because lead ions contain 82 protons. Another period of careful adjustment was needed before lining the beams up for collision, and then finally declaring that nominal data taking conditions, known at CERN as stable beams, had been established. The three experiments recording data with lead ions, ALICE, ATLAS and CMS can now look forward to continuous lead-ion running until CERN’s winter technical stop begins on 6 December.</p>
<p>“It's been very impressive to see how well the LHC has adapted to lead ions,” said Jurgen Schukraft, spokesperson of the ALICE experiment. “The ALICE detector has been optimised to record the large number of tracks that emerge from ion collisions and has handled the first collisions very well, so we are all set to explore this new opportunity at LHC.”</p>
<p>“After a very successful proton run, we’re very excited to be moving to this new phase of LHC operation,” said ATLAS spokesperson Fabiola Gianotti. “The ATLAS detector has recorded first spectacular heavy-ion events, and we are eager to study them in detail.”</p>
<p>“We designed CMS as a multi-purpose detector,” said Guido Tonelli, the collaboration’s spokesperson, “and it’s very rewarding to see how well it’s adapting to this new kind of collision. Having data collected by the same detector in proton-proton and heavy-ion modes is a powerful tool to look for unambiguous signatures of new states of matter.”</p>
<p>Lead-ion running opens up an entirely new avenue of exploration for the LHC programme, probing matter as it would have been in the first instants of the Universe’s existence. One of the main objectives for lead-ion running is to produce tiny quantities of such matter, which is known as quark-gluon plasma, and to study its evolution into the kind of matter that makes up the Universe today. This exploration will shed further light on the properties of the strong interaction, which binds the particles called quarks, into bigger objects, such as protons and neutrons.</p>
<p>Following the winter technical stop, operation of the collider will start again with protons in February and physics runs will continue through 2011.</p>
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<p>CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. Israel is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.</p>
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Mon, 08 Nov 2010 09:00:00 +0000Cian O'Luanaigh117 at http://press.cernThe LHC enters a new phasehttp://press.cern/press-releases/2010/11/lhc-enters-new-phase
<span class="submitted-by">04 Nov 2010</span>
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<a href="http://press.cern/sites/press.web.cern.ch/files/image/press/old/lead%20ion.jpg"><img typeof="foaf:Image" src="http://press.cern/sites/press.web.cern.ch/files/image/press/old/lead%20ion.jpg" width="561" height="374" alt="" /></a> </div>
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<p>Detlef Kuchler, a physicist in CERN's Beams department, holds a piece of the lead source material used to create heavy ions for the LHC. Photo: M. Brice / CERN</p>
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<p>Geneva, 4 November 2010. Proton running for 2010 in the LHC at CERN<sup><a href="#footnote1">1</a></sup> came to a successful conclusion today at 08:00 CET. Since the end of March, when the first collisions occurred at a total energy of 7 TeV, the machine and experiment teams have achieved all of their objectives for the first year of proton physics at this record energy and new ground has been explored. For the rest of the year the LHC is moving to a different phase of operation, in which lead ions will be accelerated and brought into collision in the machine for the first time.</p>
<p>A major target for 2010 was to reach a luminosity – a measure of the collision rate – of 10<sup>32</sup> per square centimetre per second. This was achieved on 13 October, with two weeks to spare. Before proton running came to an end, the machine had reached twice this figure, allowing experiments to double the amount of data collected in the space of only a few days.</p>
<p>“This shows that the objective we set ourselves for this year was realistic, but tough, and it’s very gratifying to see it achieved in such fine style,” said Rolf Heuer, CERN’s Director General. “It’s a testimony to the excellent design of the machine as well as to the hard work that has gone in to making it succeed. It bodes well for our targets for 2011.” The main goal for 2011 is for the experiments to collect enough data – an amount known by the physicists as one inverse femtobarn - to make significant advances across a broad frontier of physics.</p>
<p>The LHC experiments have already entered new territory with their first measurements at a total energy of 7 TeV. The results so far have included the validation of aspects of the Standard Model of particles and forces at these new high energies; the first observations of the top quark in proton-proton collisions; limits set on the production of certain new particles, for example “excited” quarks; and hints of effects in proton-proton collisions that may be linked to previous observations in the collisions of heavy ions. </p>
<p>“The experiments are already providing an exciting glimpse of the new frontier”, said Sergio Bertolucci, Director for Research and Computing. “This rapid delivery of the first physics measurements at 7 TeV is a direct result of the excellent performance of the detectors, the high efficiency of the data collection and the swift distribution of data via the Worldwide LHC Computing Grid for analysis at centres across the globe.”</p>
<p>The Worldwide LHC Computing Grid (WLCG) combines the computing power of more than 140 independent computer centres in 34 countries and supports the LHC experiments. It handles more than a million computing jobs a day with hundreds of physicists performing data analysis. Data has been transferred at impressive rates, witnessing peaks of 10 gigabytes per second, the equivalent of two full DVDs of data a second.</p>
<p>The change to running with lead ions – lead atoms stripped of electrons - opens up an entirely new avenue of exploration for the LHC programme, probing matter as it would have been in the first instants of the Universe’s existence. One of the main objectives for lead-ion running is to produce tiny quantities of such matter, which is known as quark-gluon plasma, and to study its evolution into the kind of matter that makes up the Universe today. This exploration will shed further light on the properties of the strong interaction, which binds the particles called quarks, into bigger objects, such as protons and neutrons.</p>
<p>“Heavy-ion collisions provide a unique micro-laboratory for studying very hot, dense matter,” said Jurgen Schukraft, spokesperson of the ALICE experiment, which is optimized to study lead-ion collisions at the LHC. “At the LHC we’ll be continuing a journey that began for CERN in 1994, which is certain to provide a new window on the fundamental behaviour of matter and in particular the role of the strong interaction.”</p>
<p>The WLCG faces a new challenge with lead-ion collisions, as the flow of data will be significantly greater than for proton-proton collisions. Recent tests have demonstrated the readiness of the data storage system at CERN to accept data at more than three times the rate achieved for proton-proton collisions, and more than double the rate originally anticipated for heavy ions.</p>
<p>The LHC will run with lead ions until 6 December, before a technical stop for maintenance. Operation of the collider will start again with protons in February and physics runs will continue through 2011.</p>
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<p>CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. Israel is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.</p>
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Thu, 04 Nov 2010 09:00:00 +0000Cian O'Luanaigh119 at http://press.cern